Method and apparatus for treating vascular occlusions

ABSTRACT

An intravascular catheter system for the treatment of occluded blood vessels that includes tissue displacement or hinged expansion members that are movable from a closed to an open position. An actuating assembly may be provided for moving the tissue expansion members between an open and closed position to exert a substantially lateral distal end force upon the region surrounding an occluded blood vessel. The tissue expansion members may stretch apart, tear or otherwise disrupt a vascular occlusion sufficiently to create a pathway that may support the passage or placement of a guidewire or an interventional vascular device across the occlusion or obstruction. Methods of crossing or displacing a vascular occlusion are further provided that include the positioning of a vascular catheter having at least one hinged spreading member positioned at the distal region of the catheter that is responsive to directed force along the longitudinal axis of the catheter. A directed force is applied to the actuator in order to deploy the spreading member and displace a vascular occlusion creating a path to permit the passage of a guidewire or device therethrough.

This patent application is a continuation of U.S. patent applicationSer. No. 09/149,874, filed Sep. 8, 1998, which is a continuation-in-partof U.S. patent application Ser. No. 08/775,264, filed Feb. 28, 1997which claims priority of U.S. Ser. No. 60/050,913 filed Feb. 28, 1997.

FIELD OF THE INVENTION

The invention is generally directed to medical devices and cathetersdesigned for the treatment vascular occlusions. More particularly, theinvention is directed to cardiovascular catheters having the ability tosufficiently fracture, disrupt or displace a vascular occlusion in orderto allow a guidewire to pass through the occlusion within the lumen of ablood vessel. The invention is further directed to a vascular catheterfor crossing a substantially occluded blood vessel by disrupting theocclusion to provide a pathway that permits the passage of a guidewireor interventional cardiovascular device such as a stent or othercatheter apparatus.

BACKGROUND OF THE INVENTION

Medical science has long sought effective treatments for disease statesthat cause stenosis (narrowing or obstruction) of the lumen (interiorpassage of the artery) of an artery. This condition, known generally asa vascular occlusion, is found in patients suffering from the disease ofatherosclerosis (an accumulation of fibrous, fatty or calcified tissuein the arteries). Symptoms of arterial occlusion include hypertension(high blood pressure), ischemia (deficiency of circulation), angina(chest pain), myocardial infarction (heart attack), stroke, or death. Anocclusion may be partial or total, may be soft and pliable or hard andcalcified, and may be found at a great variety of sites in the arterialsystem including the aorta, coronary and peripheral arteries.

Of particular interest to cardiac medicine are the often disabling orfatal occlusions occurring in the coronary arteries (arteries supplyingthe heart). Traditionally, coronary artery occlusions have been treatedby performing coronary bypass surgery. This is a procedure in which asegment of the patient's saphenous vein may be taken from the patient'sleg and is grafted onto the affected artery at points proximal(upstream) and distal (downstream) to the occluded segment. While theprocedure can improve the patients quality of life through reducedischemia and angina, it is major surgical procedures with significantmorbidity and mortality risks and a long convalesce period.Consequently, it is contraindicated for a significant portion of thepatient population due to age and other factors. Moreover, in asignificant percentage of patients, the saphenous vein graft may becomeoccluded over the passage of time due to same disease processes whichcaused the original occlusion. If the patient has another saphenousvein, a second bypass procedure may be performed, once again incurringthe risk, cost and prolonged hospitalization of this procedure. In factup to 25% of bypass patients may require repeat surgery.

Newer, minimally invasive procedures are now preferred in the treatmentof arterial occlusions. These procedures often include the use of long,thin, and highly flexible devices known in the art as catheters. Duringthe procedure, the catheter is introduced into a major artery through asmall arterial puncture made in the groin, upper arm, or neck, and isadvanced and steered into the site of the stenosis. At the distal end ofthe catheter, various devices have been developed for operating upon thestenosed artery. For example, the more popular minimally invasiveprocedures include percutaneous transluminal coronary angioplasty(PTCA), directional coronary atherectomy (DCA), and stenting. PTCAemploys a balloon to mechanically dilate the stenosis. In PTCA, asteerable guidewire is introduced and advanced under fluoroscopicobservation into the narrowed artery and past the area of stenosis (e.g.blockage). Next, a balloon-tipped catheter is advanced over theguidewire until it is positioned across the stenosed segment. Theballoon is then inflated, separating, fracturing or otherwise deformingthe atheroma so as to enlarge the narrowed lumen of the arterysufficiently to increase blood flow to a previously ischemic or nearischemic section of the myocardium. Directional coronary atherectomy isanother minimally invasive procedure that has been developed, a cathetercontaining a cutter housed in its distal end is advanced over theguidewire into the stenosed segment. The housing is urged against theatheroma by the inflation of a balloon, so that part of the atheromaintrudes through a window in the side of the housing. Under fluoroscopicobservation, the cutter is used to shave away the atheroma. The shavingsare collected in the nosecone of the housing and withdrawn along withthe catheter. Similarly, stenting is another current procedure in whicha wire framework, known as a stent, is compressed and delivered aballoon catheter. The stent is positioned across the stenosed segment ofthe artery. The balloon is inflated, dilating the stent and forcing thestent against the artery wall. The hoped-for outcome is that the stentwill hold the arterial lumen open for a prolonged period. Frequently, astent is placed in an artery immediately following PTCA or DCA. Thecatheters selected for many of the aforementioned procedures are knownas “over-the-wire catheters.” These catheters depend upon thepositioning of a guidewire, which typically has a flexible portion atits distal end for steering. Over-the-wire catheters cannot bepositioned adjacent the stenosis to carry out current procedures untilthe guidewire traverses or has been advanced across the stenosedarterial segment. Thus, where the occlusion is too severe to be crossedby a guidewire or where there is not enough room for the balloon,cutter, or stent delivery catheter, neither PTCA nor DCA nor stentingcan be effectively performed.

Unfortunately, vascular occlusions often contain extremely hard,calcified tissue that forms an impenetrable barrier against the simpleadvancement of a guidewire across the occlusion. Even a less than totalocclusion may contain complex structures which may trap or divert thesteering end of the guidewire. Thus, the guidewire may not completelycross the occlusion, and may become diverted into the subintimal spacebetween the atheroma and the arterial wall, or even become buried in theatheroma. In either case, the guidewire cannot be properly positionedacross the stenosis to guide a balloon or cutting element. In suchcases, bypass surgery may be necessary with the associated cost, risks,and recovery period. Thus, in patients suffering from severe or totalarterial occlusion, it is preferable to do what has been difficult orimpossible in the past, to open the severely or totally occluded arteryitself, rather than by performing a bypass. If a guidewire and workingcatheter can be passed through or around the atheroma, the occlusion canbe treated by a number of interventional procedures include PTCA, DCA,stenting, site-specific drug and radiation delivery or a combination ofthese different therapies.

Accordingly, it would be medically advantageous to circumvent a vascularocclusion. Appropriate devices and procedures for crossing the occlusionshould be selected without perforating the blood vessel or artery beingtreated, an extremely serious and even life-threatening consequence. Aphysician will generally not use a system which would be unsafe, norwould patients want a physician to use such a system. Therefore,solutions to the problem of crossing a vascular occlusion such as anatheroma should be safe, and in many instances, include a system ofguidance for the device to bypass such an occlusion. There has been along felt need in the practice of interventional cardiology andradiology for a reliable guidance system for these types of vasculardevices. As understood by those in the art, the device often travelsthrough a complex, tortuous vascular anatomy before it even gets to theocclusion. Then the occlusion itself often has a irregularly shaped(e.g. eccentric) morphology. Attempting to cross such an occlusionwithout reliable imaging of the adjacent vasculature is dangerous. Forexample, it is easy to dissect the tissues of the arterial wall insteadof the occlusion, thereby creating a false lumen and possiblyperforating the artery. If enough blood from a perforated arteryaccumulates in the pericardial space surrounding the heart, it willresult in a condition known as cardiac tamponade in which the heart iscompressed and emergency surgical intervention is required to avertheart failure and death. Physicians have attempted to avoid such adverseevents through the use of imaging systems/procedures such as biplanefluoroscopy. This is an imaging system that has been used in conjunctionwith coronary catheterization wherein the physician observes two flatreal-time x-ray images acquired from different angles. However, biplanefluoroscopy may be unreliable, costly, and relatively slow. Delay isunacceptable in many instances, for it contributes to trauma and stressand creates opportunities for complications and failures of technique.While advanced medical imaging systems may be of diagnostic interest,they are not a substitute for effective interventional treatment forsevere occlusive arterial disease. There persists a long felt need inthe art for a vascular device which is capable of successfully crossingan arterial occlusion with a relatively low risk of perforating theartery. What is especially needed is a therapeutic working device whichassists the physician in safely restoring normal blood flow rates withindiseased blood vessels. What is further needed is a vascular cathetersystem that may allow effective treatment of a severely occluded arteryand, in particular, a totally occluded artery.

SUMMARY OF THE INVENTION

The present invention provides methods and apparatus for the treatmentof vascular occlusions. It is an object of the invention to disruptvascular occlusions or other blockages formed within blood vessels inorder to provide pathways for the placement of guidewires,interventional devices and catheters as part of an overall effort torestore normal circulatory function. It is advantageous to cross avascular occlusion by finding and/or creating a path with the least orrelatively low mechanical resistance through or around the occlusion.The invention further provides apparatus and methods to tear or tomechanically fracture a vascular occlusion, or to separate a vascularocclusion from a blood vessel wall, with minimal risk of perforating theadventitia of an arterial wall.

One aspect of the invention provides apparatus for treating a vascularocclusion. A catheter may be selected comprising an elongated shaft thatis formed with at least one lumen extending from the proximal section tothe distal section of the shaft. A hinged spreading member may bepositioned at the relatively distal section of the shaft. The spreadingmember may include a distal most end that moves in a substantiallylateral direction away from the central axis of the shaft to disrupt avascular occlusion. An actuating assembly may be also positioned alongat least a portion of the elongated shaft to move or to direct thedistal most end of the spreading member in response to an appliedactuation force. The actuating assembly may further include a camfollower or other guiding region that is formed on a relatively interiorportion of the hinged spreading member.

Another embodiment of the invention includes an intravascular catheterfor expanding or stretching vascular tissue. The intravascular tissueexpanding catheter may include a catheter shaft defined by a distal endhaving at least one conduit extending along the longitudinal axis of thecatheter shaft. A housing may be formed at the distal end of thecatheter shaft wherein the housing includes at least one hingeddeflecting member defined by a distal most tip that moves in asubstantially lateral direction away from the central axis of the shaftto expand tissue surrounding a vascular occlusion. An actuation assemblymay be also positioned along the catheter shaft to move the distal mosttip of the hinged deflecting member away from the central axis of theshaft. The catheter shaft may be also formed of braided material and aflexible inner coil shaft component that supports a column load.

It is a further object of the invention to provide a vascular catheterthat is formed with a tissue expansion assembly for tearing orfracturing an occlusion within a blood vessel. The vascular catheter maycomprise a catheter body formed with a distal section and at least onelongitudinal conduit. At least one tissue expanding member may beconnected to the distal section of the catheter body. The expandingmember may include a relatively proximal portion and a relatively distalportion wherein the distal portion is configured to spread apartrelative to the proximal portion of the expanding member. An actuationassembly may be positioned within the catheter body, and may be incommunication with the proximal portion of the tissue expanding memberto spread apart the distal portion of the expanding member. The distalsection of the catheter may further include a relatively fixedextension. The relatively proximal portion of the tissue expandingmember may be connected to the fixed extension with a hinge pin topermit the relatively distal portion of the tissue spreading member tomove away from the fixed extension.

It is an additional object of this invention to provide flexiblecatheter shafts that support variable column loads. The shaft maycomprise an outer catheter shaft defined by a longitudinal shaft lumen.An inner coiled body that is defined by a longitudinal coiled lumen maybe positioned within the longitudinal shaft lumen for column loadreinforcement of the outer shaft. A movable pulling element may beslidably positioned within the longitudinal coiled lumen for relativemovement of the pulling element with respect to the inner coiled body.Another variation of the invention is to provide a catheter shaft with areinforced outer catheter shaft. An outer shaft may be formed with alumen that includes an inner shaft positioned within the outer shaftlumen. The inner shaft may further include an actuation lumen and atleast one inner shaft lumen, and may be formed by extrusion. A columnload reinforcement sleeve may be formed with a sleeve lumen that ispositioned within the actuation lumen. In addition, an actuation wiremay be slidably positioned within the sleeve lumen to provide relativemovement of the wire within the sleeve. At least one inner shaft lumenmay be also configured for placement of a guidewire. In yet anothervariation, a reinforced catheter body may be selected having a braidreinforced catheter shaft formed with a longitudinal catheter shaftlumen. An actuation conduit and a guidewire conduit may be separatelyformed within the longitudinal lumen of the catheter shaft.Additionally, a compression or wound coil that provides compressionsupport may include a coil lumen and may be positioned within theactuation conduit for column load reinforcement of the actuationconduit. A pulling element may be positioned within the coil lumen forrelatively slidable movement within the coil.

Another object of the invention is to provide an intravascular catheterfor expanding tissue that includes a catheter body formed with an outerreinforced shaft coaxially formed about an inner coiled body for columnload reinforcement of the catheter body. The inner coiled body mayfurther include an actuation conduit leading to a relatively distalsection of the catheter body. A tissue expanding member may be connectedto the distal section of the catheter body. The interior surface of thetissue expanding member may include a cam follower. Additionally, theexpanding member may be defined by a relatively proximal portion and arelatively distal portion so that the distal portion is configured toexpand relative to the proximal portion of the expanding member. Anactuation element may be selected and positioned within the actuationconduit formed in the inner coiled body. The actuation element may beformed as a wire or tube that supports actuation forces, and may furtherinclude a cam for communication with the interior cam follower of thetissue expanding member to expand the distal portion of the expandingmember when actuated. The surface of the cam includes a variety ofcurved or non-linear configurations, and is preferably complementary tothe shape of the corresponding cam follower.

Another aspect of the invention includes methods for disrupting andcrossing a vascular occlusion. The vascular occlusion may be separated,fractured or displaced to provide a pathway across the obstruction inorder to accommodate the placement of a guidewire or interventionaldevice as part of an overall effort to restore normal circulatoryfunction within the blood vessel.

It is an object of the invention to provide methods of displacing avascular occlusion by initially selecting a vascular catheter that isformed with a spreading member positioned at the distal region of thecatheter. The spreading member may be configured to spread or stretchapart an occlusion and/or vascular tissue, and may be activated oractuated in response to a directed force along the longitudinal axis ofthe catheter. An actuator assembly may be positioned along at least aportion of the catheter to transmit the directed force which may beapplied linearly or rotationally, or by transmitting pressure relativelydistally to an actuation balloon, from a remote or proximal portion ofthe catheter to the spreading member. The vascular catheter may bepositioned adjacent to a substantial or total vascular occlusion withina selected blood vessel before applying a directed force to the actuatorin order to deploy or to spread apart the spreading member. Theocclusion may be displaced or disrupted based upon the different elasticproperties between stretchable blood vessel walls and materials whichform vascular occlusions. The vascular occlusion itself may be alsofractured or otherwise disrupted to provide a passageway across theocclusion in order to accommodate the placement of a guidewire orinterventional device such as a stent after removing the vascularcatheter from the selected blood vessel. The spreading member may bespread apart to disrupt a vascular occlusion to create a pathsubstantially through or around at least a portion of the occlusion.Additionally, the spreading member may stretch out the blood vessel wallcreating a path substantially between the occlusion and the blood vesselwall. When the vascular occlusion is adhered to the wall of a selectedblood vessel, the spreading member may be also expanded or spread apartto separate the layers of the blood vessel wall. The vascular cathetermay be distally advanced through the vascular occlusion to pass throughat least a portion of or entirely through the occlusion. Anothervariation of the invention includes the method of selecting a guidewireand passing the guidewire through a conduit formed in the vascularcatheter. The guidewire may extend along to the length of the catheterand reach the site of an occlusion. Upon activation of at least onespreading member, the guidewire may be advanced through or around atleast a portion of the occlusion.

Other various methods of crossing a substantially occluded blood vesselare provided herein in accordance with the concepts of the invention. Anintravascular catheter may be selected that includes a distally mountedtissue expanding member defined by a relatively proximal portion and arelatively distal portion so that the distal portion is configured toexpand relative to the proximal portion of the expanding member. Inaddition, an actuation assembly may be positioned within theintravascular catheter to transmit a spreading force in order to expandthe distal portion of the expanding member. The tissue expanding membermay be placed or positioned within a blood vessel in proximity to anocclusion, and subsequently activated to stretch the blood vessel walland disrupt the occlusion to permit the passage therethrough. The tissueexpanding member may be deactivated thereafter, and the intravascularcatheter removed from the target blood vessel. A guidewire may bepositioned within the passageway formed within or alongside thedisrupted or displaced occlusion in order to facilitate the placement ofa stent or other interventional device. The guidewire may also passthrough at least a portion of the occlusion before the tissue expandingmember is deactivated. The catheter may be similarly advanced through oracross at least a portion of the occlusion upon disruption of thevascular obstruction.

In yet another variation of the invention, a method is provided forcrossing a coronary vascular occlusion. This procedure may begin byselecting and advancing a guidewire within a blood vessel to a vascularocclusion. An intra-coronary guiding catheter may be advanced over theguidewire so that the distal end of the catheter is in proximity to thevascular occlusion. The guidewire may be thereafter removed from theblood vessel. An intravascular catheter may be selected for placementwithin the guiding catheter that includes a spreading member positionedthat is responsive to directed force along its longitudinal axis.Additionally, an actuator assembly may be positioned along theintravascular catheter to transmit a directed force applied from theproximal portion of the catheter to the spreading member. Theintravascular catheter may be advanced through the intra-coronaryguiding catheter to position the spreading member of the intravascularcatheter substantially adjacent to the vascular occlusion within theblood vessel. A directed force may be applied to the actuator assemblyto spread apart the spreading member in order to displace the vascularocclusion. Another variation of this method may include the advancementof the intra-coronary guiding catheter past or across the occlusionbefore removing the intravascular catheter from the blood vessel. Inaddition, a guidewire may be advanced past or across the displacedvascular occlusion after removing the intravascular catheter and beforeremoving the intra-coronary guiding catheter.

Other variations of the invention described herein include a vascularcatheter formed with a blunt end assembly for tearing or fracturing anocclusion within a blood vessel. It is an additional object of thisinvention to provide such an assembly wherein the assembly includes acatheter having a distal end and a proximal end and wherein a workingend member fits in an interchangeable manner to the distal end of thecatheter and wherein the working end comprises a blunt end member inaccordance with the invention. It is an additional object of thisinvention to provide such an assembly wherein the blunt end member has afirst closed position and a second open position and may be repeatedlyopened and closed for tearing/fracturing the occlusion within the lumenof the blood vessel. It is a further advantage of the invention toprovide a tearing or fracturing force that is stably applicable to asevere or total arterial occlusion. A mechanical working element may bestably operable upon a severe or total arterial occlusion in a mannerunlikely to perforate the adventitia or other layers of the arterialwall. In addition, the blunt end member assembly may comprise: a bluntend member connectable to the distal end of the catheter, the blunt endmember sized and shaped for fitting within the blood vessel and fortearing and/or fracturing the occlusion, the blunt end member having afirst position for allowing the blunt end member to be located at theocclusion and a second position for fracturing the occlusion; and anactuation member for moving the blunt end member between the first andsecond positions, whereby the blunt end member is connectable to thedistal end of the catheter and the blunt end member is deliverable tothe occlusion in the first position and is actuable to a second positionfor fracturing the occlusion.

In one embodiment of the invention, an over-the-wire vascular catheteris provided comprising a blunt end member disposed at the distal endthereof and a securing balloon disposed about the distal end zone of thecatheter proximal to the blunt end member. The catheter and blunt endmember may be sized and shaped so as to allow the blunt end member to beadvanced into contact with an occlusion in an artery. The balloon may bedisposed on the outer surface of the distal end zone of the catheter andis inflatable to secure the distal end of the catheter within theartery, and thus to maintain engagement or longitudinal registration ofthe blunt end member with the occlusion. A balloon inflation lumen maybe provided in the catheter. The blunt end member may comprise four jawsections flexibly attached to the distal end of the catheter, and may bearranged symmetrically about the longitudinal axis thereof The cathetermay comprise a retractable actuation shaft having a ball-shaped ferrulefixed to the distal end thereof between the jaw sections. To accommodatea guidewire, the actuation shaft may include a lumen and the ferruleincludes a center opening. The jaw sections may have a first, closedposition in which the catheter may be advanced to engage the jaws withthe occlusion. When the actuation shaft is retracted, the ferrule or camimpinges upon the inner surfaces or cam followers of the jaw sections,urging them apart toward a second, open position to fracture theocclusion. The ferrule may be formed with a fiusto-conical profile.

In another embodiment of the invention, each jaw section may include arectangular distal end or a spade-shaped configuration. In the first,closed position, the jaw sections form a channel substantially confiningthe guidewire to the longitudinal axis of the blunt end member. It is anadvantage of this embodiment that when the jaw sections are in thefirst, closed position, a guidewire may be advanced into a portion ofthe occlusion bounded by the points of contact with the distal ends ofthe jaw sections. In another embodiment of the invention, the jawsections may be fabricated from an alloy comprising nickel and titanium.It is an advantage of this exemplary embodiment of the invention thatthe superelastic properties of the alloy facilitate closing of the jawsections when the ferrule is deactivated or de-actuated by an actuationmember.

In another exemplary embodiment of the invention, the actuation memberincludes an actuation cable disposed in the catheter. The proximal endof the cable is manipulable from the proximal end of the catheter andthe distal end of the cable is attached to the ferrule. It is anadvantage of this exemplary embodiment of the invention that the cableincreases the tension capacity of the actuation member during retractionof the ferrule. A part of the lumen of the actuating member may includea friction reducing coating. It is an advantage of this embodiment ofthe invention that the catheter slide easily over the guidewire. Inanother embodiment of the invention, the mating surface defined by theimpingement of the actuation member upon the blunt end member includes afriction reducing coating. It is an advantage of this exemplaryembodiment of the invention that the actuation member encounters minimalfrictional resistance while urging the jaw sections apart.

In another embodiment of the invention, the entire blunt end member maybe fabricated from a single piece of material. It is an advantage ofthis exemplary embodiment of the invention that fabrication of the bluntend member does not require attachment or assembly of multiple parts.

Another embodiment of the invention provides a blunt end member thatincludes a rigid tubular reinforcing member slidably disposed about theactuation shaft inside the distal end zone of the catheter. A tubularsupport member is disposed on the outer surface of the distal end of thecatheter. The distal end of the support member includes a spring memberdeformably supporting a plurality of jaw sections. The support membermay be crimped onto the distal end zone of the catheter, securing thecatheter onto the reinforcing member. It is an advantage of thisembodiment of the invention that a simple yet secure attachment isformed between the catheter and the blunt end member.

These and other objects and advantages of the invention will become moreapparent upon further consideration of the specification and drawings.For further understanding of the objects and advantages of theinvention, reference may be made to the following description inconjunction with some of the accompanying drawings in which similarcomponents are identified with similar reference numerals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating occlusion treatment apparatuspositioned within an occluded blood vessel.

FIG. 2 is a side view of a catheter having tissue expansion memberssimilarly shown in FIG. 1 that are in the process of fracturing ortearing a total occlusion.

FIG. 3 is an enlarged side view of tissue expansion or blunt end membershaving a first closed position and a second open position.

FIG. 4 is an end view of tissue expansion members illustrated in FIG. 3that are shown in a closed position.

FIG. 5 is a cross-sectional view of hinged spreading members shown in arelatively closed position.

FIG. 6 is a cross-sectional view of hinged spreading members similarlyillustrated in FIG. 5 that are shown in a relatively open position.

FIG. 7 is a cross-sectional view of hinged deflecting members inaccordance with the invention that are shown in a closed position.

FIG. 8 is a cross-sectional view of the hinged deflecting memberssimilarly shown in FIG. 7 that are shown in an open position.

FIG. 9 is an end view of the deflecting members illustrated in FIG. 7shown in a relatively closed position.

FIG. 10 is an end view of the deflecting members illustrated in FIG. 8shown in a relatively open position.

FIGS. 11A-C are side views of a deflecting member housing assembly witha hub and hinged deflecting members.

FIGS. 12A-B are cross-sectional views of a vascular tissue expansion andactuation assembly formed with deflecting members shown in an closed andopen position.

FIG. 13 is a simplified side view of a hinged deflecting member assemblyshown in an open and closed position.

FIGS. 14A-D are simplified partial side views of various configurationsfor tissue expansion members.

FIGS. 15A-B are side views of distal mounted spreading members with anactuating balloon that spreads open the distal end portions of thespreading members.

FIGS. 16A-D illustrate various distally mounted deflecting memberassemblies formed with a plurality of deflecting members.

FIGS. 17A-B are side views of a vascular tissue expansion assembly witha single hinged member connected to a pulling element.

FIGS. 18A-D are simplified views of a hinged deflecting member andpositioning with a guidewire.

FIGS. 19A-E are simplified side and cross-sectional views of a cathetershaft with distally mounted expansion members and guidewire guidingpathways.

FIGS. 20A-C are simplified cross-sectional side views of a vasculartissue expansion assembly with various actuation and cam assemblies fordeflection of a single hinged deflecting member.

FIGS. 21A-B are side and cross-sectional views of a hinged expansionmember that may be rotationally actuated.

FIGS. 22A-B show side and cross-sectional views of a catheter shaft,under an embodiment.

FIGS. 23A-B show side and cross-sectional views of a catheter shaft,under an alternative embodiment.

FIGS. 24A-B show side and cross-sectional views of a catheter shaft,under another alternative embodiment.

FIGS. 25A-C are simplified perspective views of a proximally positionedactuation assembly formed with a lever for use by an operator.

FIGS. 26A-B are cross-sectional views of an expansion member assemblyhaving multiple deflecting members within an occluded blood vessel in anopen and closed position.

FIGS. 27A-B are cross-sectional views of an expansion member assemblyhaving a single deflecting member within an occluded blood vessel in anopen and closed position.

FIGS. 28A-I are simplified diagrams illustrating methods for crossing acoronary occlusion with apparatus and procedures provided in accordancewith the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides methods and apparatus for disrupting andcrossing a vascular occlusion. Each of the disclosed embodiments may beconsidered individually or in combination with other variations andaspects of the invention. While some variations of the inventionillustrated herein may seem particularly directed to coronary arteryapplications and bypass grafts, the drawings are illustrative only, andit should be understood that the invention is similarly applicable toany blood vessel that may become obstructed due to various conditionsincluding vascular disease.

FIGS. 1 and 2 generally provide illustrations of an intravascularcatheter formed in accordance with the principles of the presentinvention. The catheter may be used to disrupt an occlusion formedwithin various sections of arterial or venous blood vessels. Thecatheter may include a housing or blunt end member assembly formed witha relatively proximal portion attached to a distal end of an elongatedcatheter shaft by applying adhesive, crimping or other joiningtechniques. The housing may be further defined by a relatively distalportion that is configured for intimate contact or communication with anocclusion and/or a blood vessel wall. The distal mounted housing mayfurther include one or more hinged spreading or deflecting members thatmay be mechanically activated by an actuating member such as a pull wireor tube. A spreading or mechanical force may be thus applied to theblood vessel wall and occlusion so as to tear, fracture or otherwisedisrupt, the occlusion adjoining the vessel wall. This disruption of theocclusion may create a channel or a passageway of sufficient size forthe passage of a guidewire or therapeutic catheter around or through atleast a portion of the obstruction as part of an overall effort torestore regular circulatory function surrounding the occluded vascularregion.

With particular reference to FIG. 1, there is shown a blunt end memberassembly formed in accordance with this invention, generally designatedby the numeral 20. The assembly 20 may include a blunt end member 22 anda catheter 24. An actuation member indicated by dotted lines 26 may moveor actuate the blunt end member from a first closed position, asillustrated in FIG. 1, to a second open position, as illustrated in FIG.2. The catheter may be initially positioned using a guidewire 28 so thatthe extreme distal end of the blunt end member 22 may be adjacent to asubstantial or total occlusion. Once positioned, the catheter 24 mayremain relatively fixed at a particular location with a member forstabilizing the assembly 20 in a blood vessel, namely, a balloon member30. The balloon member 30 may be inflated as shown in FIG. 2 so that thecatheter 24 remains in place during actuation of the blunt end member22.

As illustrated in FIGS. 1 and 2, the blunt end member 22 may bepositioned at various blood vessel junctures including a locationadjacent to a total occlusion where a bypass is in the process offailing. The bypass may develop diffuse stenosis as shown in FIGS. 1 and2. Consistent with the above description, it is quite likely that wherestenosis has developed sufficiently to block an arterial blood vessel,after a bypass is performed, stenosis in the bypass will also occur oraccumulate even to a point where the bypass may be also blocked orbecome totally occluded. Using a blunt end member 22 formed inaccordance with the invention, the original, native blood vessel may bere-opened which allows the bypass to fade as the primary source of bloodflow. It should be noted that different aspects of the inventionillustrated herein describe methods and apparatus directed particularlyto native coronary arteries. However, it will be of course appreciatedthat the drawings are illustrative only, and that the invention may beapplied to any situation where a blood vessel, such as a coronaryartery, has been occluded by stenosis or vascular disease. Among otherfeatures provided herein, the invention disrupts or fractures occlusionsto allow a native artery or blood vessel to resume its primaryresponsibility of supporting blood flow.

FIGS. 3-6 provide further illustrations of a blunt end member 22 havingvarious open and closed positions. The blunt end member 22 may be formedwith a proximal end attached to the distal end of a catheter 24. Themethods of attachment for the blunt end member 22 include conventionaltechniques within the skill and knowledge of those skilled in the art.The blunt end member 22 may include a set of sectional members definingthe jaw sections 42. The jaw sections 42 may be located at the distalend of the blunt end member 22, and may be spaced apart at equaldistances relative to a longitudinal center line 44 shown in FIG. 3. Thejaw sections 42 may be opened to a second position shown particularly inFIGS. 3 and 6, and may be closed or returned to a first position asshown in FIGS. 3-5. An actuation wire or actuation member 54 may beprovided within the assembly to move the jaw sections 42 from its firstclosed position to its second open position. In various embodiments, thejaw sections 42 may have a variety of geometries, including but notlimited to, spade shaped, straight with a concave curve at the end,straight with convex curve at the end, triangular (needle nose),rectangular and combinations thereof. The jaws 42 may be spaced apart orseparated from one another even when closed as shown in FIG. 4. Thisconfiguration may allow the jaw sections 42 to meet relatively flushagainst an arterial wall and an occlusion for optimal fracturing ordisruption of the occlusion.

With respect to FIGS. 5 and 6, there is shown an assembly view ofanother the blunt end member 22 formed in accordance with the invention.The blunt end member 22 may include a reverse conical urging member 50and a spaced apart support member 52. The members 50 and 52 may be sizedand shaped to fit within the same cavity or lumen of a catheter 24. Eachof the members 50 and 52 may include a center opening along alongitudinal center line of the assembly. The openings of members 50 and52 may be aligned so that a guidewire tube 54 may be positioned in theopenings to slide toward and away from the proximal end of the catheter24. A ferrule 56 may be attached to or bonded together with theguidewire tube 54 as shown in FIGS. 5 and 6. The bonding techniques usedmay be similar to those for joining the catheter 24 and the blunt endmember 22. Additionally, bonding may be done by use of adhesives such ascyanoacrylate, soldering, or chemical or physical bonding, of a suitablekind. The guidewire tube or actuation member 54 being thus, permanentlyconnected to the ferrule 56 in a bond which is strong enough towithstand the urging forces exerted against an occlusion. The ferrule 56may also have a center opening aligned with the center openings of themembers of 50 and 52. However, the center opening of the ferrule 56 maybe formed with a relatively smaller diameter to match the dimensions ofan inner guidewire 28 as opposed to the relatively outer guidewire tube54. Alternatively, the ferrule 56 may be designed to accommodate onlythe guidewire 28 and not the guidewire tube 54. The guidewire 28 may beinserted in the center opening of the ferrule 56. The ferrule 56 may bedefined by a frusto-conical shape, while the urging member 50 forms areverse compatible shape for sliding against the fusto conical shape ofthe ferrule 56. The surfaces where each 5 of the ferrule 56 and theurging member 50 contact, define a mating surface. The materialsselected for each of the ferrules 56 and urging member 50 may becompatible for such mating sliding contact. In response to actuation,the ferrule 56 may be pulled toward the proximal end of the catheter 24causing the ferrule 56 to slide against the urging member 50 so that themating surfaces of each sliding across one another. As the ferrule ispulled towards the proximal end of the catheter, an increasing force isurged against the jaw sections 42 for spreading apart the jaw sections42. Upon full activation of the actuation member the jaws may be fullyopened as generally shown in FIG. 6. It will also be appreciated thatthe jaw sections 42 may be also spaced apart a sufficient distance whenclosed along the longitudinal center line 44 so a guidewire may beguided thereby as shown in FIGS. 3-5. The jaw sections 42, when closed,may form an internal guide 58 for sliding the guidewire toward and awayfrom the distal end of the catheter 24. The interior opening of themembers 50 and 52 may also provide a guide for the guidewire tube 54 asthe jaw sections 42 are opened and closed in repeated use. It may beadvantageous to coat the interior opening of the members 50 and 52, aswell as the exterior of the guidewire tube 54, with Teflon® or a similarpolymer so that the friction from the movement of sliding through theinternal opening is greatly reduced. A reduction in friction may resultin more force being effectively applied by the ferrule 56 against theurging member 50 which may maximize the amount of tearing or fracturingforce applied by the blunt end member 42 to the arterial wall. Theguidewire tube 54 may be a braided strand, and thus can be quiteabrasive to the internal opening of the members of 50 and 52. Thus, theapplication of a friction-reducing coating to guidewire tube 54 ormember 50 and 52 may be particularly appropriate to reduce the frictionin the sliding movement. The guidewire tube 54 may be also a nitinolhypotube. Additionally, the mating surfaces of the urging member 50 andthe ferrule 56 may be as smooth as possible, and may be chosen fromcompatible materials which minimize the amount of friction developed asthe mating surfaces slide against one another in an effort to fracturean occlusion. In various embodiments, the urging member 50 may be madefrom nickel titanium alloy and the ferrule 56 may be constructed fromstainless steel. Again, the mating surfaces of the ferrule 56 and urgingmember 50 may be formed as smooth as possible to minimize the frictiontherebetween.

As shown in FIGS. 5 and 6, the support member 52 may provide supportboth internal and external to the assembly. The support member 52 mayremain fixedly attached to the distal end of the catheter 24, and mayprovide an internal opening for the sliding movement of the guidewiretube 54. Additionally, the jaw sections 42 have a proximal end zonewhich may surround both the urging member 50 and the support member 52.The proximal end zone of the jaw sections 42 may secure the members 50and 52 together to provide the assembly. As shown in FIG. 6, the supportmember 52 may be notched to form a shoulder 62 that provides a secureconnection fit with the jaw sections 42. In another exemplary embodimentin accordance with a unified assembly, the jaw sections 42 may benotched with an opening at elbow 64 as shown in FIG. 6. Thisconfiguration may allow space for deformation of the jaw sections 42along an axis predetermined by the angle and length of the opening. Itshould be understood that the blunt end jaw members 42 may be formed ofvarious materials with sufficient strength to withstand the mechanicalforces necessary to fracture, tear or dislodge a vascular occlusion. Ina preferable embodiment, the jaw sections may be made from nickeltitanium that is both biocompatible and has sufficient strength for thefunction intended herein. It will of course be appreciated that theentire assembly, including members 50 and 52, as well as the jawsections 42, may be formed from a single piece of nickel titanium toprovide a unified assembly. Different components of the describedassemblies may be made from a variety of materials including stainlesssteel, nickel titanium or other shape memory alloys and engineeringplastics known to those skilled in the art. Additionally, other polymersor metal materials, which are also bio-compatible and have themechanical characteristics necessary to perform the functions herein,are equally suitable.

FIGS. 7-10 illustrate yet another embodiment of a blunt end member 100formed in accordance with this invention. The blunt end member 100 mayinclude one or more jaw sections 102. A reinforcing member 108 may bepositioned between a catheter tube 24 as shown in FIGS. 7-8, and aguidewire tube 54 may be placed in the guidewire lumen of the cathetertube. A ferrule 56 may be attached to the guidewire tube 54 as discussedpreviously with regard to the other described embodiments of theinvention. The blunt end member 100 may also include a spring or hingemember 104 and a support member 106. The spring member 104 maybe formedwith a mating surface for mating with the ferrule 56. Upon actuation,the ferrule 56 may be pulled toward the proximal end of the catheter 24,and the mating surfaces may engage and separate the jaw sections 102 toan open position as shown in FIGS. 8 and 10. Upon releasing theactuation member, the spring member 104 may urge the jaw sections 102back to their original or closed positioned as shown in FIGS. 7 and 9.The spring member 104 may serve to connect the jaw sections 102 and therest of the blunt end member 100, more specifically, the support member106. The support member 106 may be crimped at its proximal end 110. Thereinforcing member 108 may be positioned so that the crimp in thesupport member 106 sandwiches the distal end of the catheter tube 24. Itwill be appreciated that the hoop strength provided by the reinforcingmember 108 may enable a secure attachment of the support member to thedistal end of the catheter tube 24. It will be further appreciated thatthe crimp in the support member, plus the added hoop strength providedby the reinforcing member 108, may provide a secure connection for theentire blunt end member 100. Typically, the blunt end member 22 may besupported by the connections at the joining of the spring 104, the jawsections 102, and support member 106. These joints can be formed in avariety of ways using adhesive bonding and metal joining methods wellknown in the art. For example, it may be preferable to bond the memberswith an epoxy, should they be made of a polymer, or to use welding,soldering, or brazing if the members are made from metal. In apreferable exemplary embodiment, the spring 104, the support member 106and the jaw sections 10 may be formed from the same material such asnickel titanium. However, other combinations of materials such as springsteel and the like are also suitable. In other embodiments, it is alsocontemplated within the scope of the invention to form the support andspring members, 106 and 104, respectively, from stainless steel.Additionally, the reinforcing member 108 may be made alternately fromnickel titanium or stainless steel. It is also contemplated that variousother types of materials are suitable for manufacturing of the blunt endmember 100 such as stainless steel and high strength medical plasticssuch as polycarbonate.

Another aspect of the invention is directed to methods of disrupting avascular occlusion with apparatus similarly shown in FIGS. 7-10. Asshown in FIG. 7, the blunt end member 100 may be placed in a firstclosed position. As is typical in interventional procedures, a guidewire28 is fed through the lumen of the blood vessels of a patient. Uponreaching the selected location, the guidewire will meet an occlusion.The blunt end member 100 with the ferrule 56 will be positioned, asdescribed earlier, directly adjacent to the occlusion. Although notshown, it will be appreciated that positioning balloons 30 may also beadapted for use with any of the embodiments shown in FIGS. 7-10. Afterstabilization or positioning of the catheter 24 in the lumen of theblood vessel, the blunt end member 100 may be activated by pulling on anactuation member 26 such that the mating surfaces of spring 104 and theferrule 56 are brought into contact with one another. The ferrule 56 maymove the jaw sections 102 away from the longitudinal center line of thecatheter. This operation may be repeated until the occlusion isfractured or broken apart, or until the occlusion is sufficientlyseparated from the inner the blood vessel wall to permit the passage ofan interventional device as described herein. As a result, the guidewire28 may be advanced through the natural lumen of the blood vessel. Thecatheter 24 may be subsequently removed, and another interventionaldevice may be positioned at or near the vicinity of the occlusion. Suchinterventional devices may include an angioplasty or atherectomy device,or a stent or other known interventional devices and methods, fortreating the occlusion once the guidewire 28 is positioned across theocclusion.

FIGS. 11A-C illustrate another embodiment of the invention that includesa vascular tissue expansion assembly 200 formed with hinged expansionmembers 202. The hinged expansion members 202 may be joined togetheraround a circumferential portion or collar 204. The collar 204 may bealso formed of multiple sections joined along a mating surface 206 byknown methods such as welding or brazing techniques, and may be furtherattached or adhesively bonded to the relatively distal end of a cathetershaft 208. The collar sections may be joined together by spot welding atselected locations 209 around the circumference of the collar 204.Specific areas in proximity to the hinge section 210 of the expansionmembers 202 may be avoided to minimize significant thermal stress tothis area, and to reduce interference with the free movement of theexpansion members. The expansion members 202 may be similarly formedfrom several portions including a nosepiece or nosecone that are joinedtogether by similar bonding or joining techniques. Although theillustrations provided include a pair of expansion members 202 joined tothe collar, any number of members may be selected for the vasculartissue expansion assembly 200.

The typical finished diameter of the tissue expansion assembly 200 mayrange from approximately 0.030″ to 0.090″, including the range from0.058″ to 0.078″, for coronary applications, and from approximately0.080″ to 0.100″, including 0.091″, for peripheral applications.Similarly, the finished length of the tissue expansion assembly 200 mayrange from approximately 0.150″ to 0.250″ for most coronaryapplications, and 0.200″ to 0.600″ for many peripheral applications.Other suitable dimensions for these components may be of course selectedand modified for particular applications.

Each expansion member 202 shown in FIGS. 11A-B may include a hingesection 210 attached to a circumferential portion of the collar 204. Theexpansion members 202 and collar 204 may be formed separately orintegrally. For example, the collar 204 and expansion members 202 may beformed of separate injection molded plastics or metals that are joinedtogether. The collar 204 may be also cylindrically shaped, and may beconnected with the expansion members 202 through other connective orhinged components that may be attached by soldering, welding or brazingor other joining techniques. Alternatively, the hinged expansion members202 and collar 204 may be integrally formed from a single piece ofselected material with techniques such as electronic discharge machining(EDM) or other formative methods well known in the art. The hingedexpansion members 202 and collar 204 sections may be formed by removingselected portions of a unitary body of material selected for theexpansion assembly 200. After the tissue expansion assembly 200 isformed, the entire assembly may be stress relieved by immersion in 520°C. potassium bath for two or more minutes followed by a room temperaturewater bath quench using known nickel titanium stress relief techniques.It should be understood that all components of the vascular tissueassembly 200, including the collar 204 and expansion sections 202, maybe manufactured from biocompatible metals or engineered plastics such asDeirin, polycarbonate or ABS, or from formable metals such as stainlesssteel or nickel titanium alloys such as 45% cold-worked Guide BB nitinolsupplied by Shape Memory Inc, CA.

As shown in FIGS. 11A-C, a catheter may be provided for treating avascular occlusion consisting of an elongated shaft 208 formed with atleast one lumen extending from the proximal section to the distalsection of the shaft. One or more hinged spreading members 202 may beformed at the distal section of the shaft 208 as part of a vasculartissue displacing assembly 200. The distal section of the elongatedshaft 208 may also include a hub 212. A collar section 204 may be fittedaround the external surface of the hub 212. In addition, one or morehinged spreading members 202 may be joined to the collar section 204 asa unitary body. The distal most end of the spreading or tissuedisplacing member 202 may move away from the central or longitudinalaxis of the shaft 208 to disrupt a vascular occlusion as illustrated inFIG. 11C. The spreading member 202 may be deflected by an actuatingassembly 220 positioned along, or at least in a part of, the elongatedshaft 208 to move the distal most end of the spreading member 202 inresponse to an actuation force. The tissue displacing member 202 may beconfigured to rotate about one end thereof away from the longitudinalaxis of the catheter shaft 208 to displace tissue surrounding a vascularocclusion. The actuating assembly 220 may be configured to be operablefrom a relatively proximal section of the elongated shaft 208.

The actuating assembly 220 may include an actuation element 222 having arelatively distal end mounted cam 224 for communication with a camfollower 226 formed in a spreading member 202 to urge the spreadingmember in a substantially lateral direction. The cam follower 226 may beformed along a relatively interior portion of the hinged spreadingmember 202. The cam 224 may be also formed with a cam edge 228 thatslidably contacts the cam follower 226 formed on the interior portion ofa spreading member 202 when the cam is moved in a relatively proximaldirection. The distal most end of the spreading member 202 may be thusarcuately moved in a substantially lateral direction.

As shown in FIGS. 12A-B, an actuation member may move the deflectingmembers 242 of a tissue displacing assembly 230 between an open andclosed position. An actuation member such as a pull tube 232 may move oractuate the deflecting or blunt end members 242 from a first closedposition as illustrated in FIG. 12A, to a second open position, asillustrated in FIG. 12B. The deflecting members 242 may be distallyjoined to an intravascular catheter (not shown), and may be configuredto remain in a closed position until the physician pulls back on theactuation member 232 in a relatively proximal direction. Theintravascular catheter may be initially positioned in an artery using aguidewire such that the distal end of the deflecting member 242 ispositioned adjacent to or at least partially within a vascularocclusion. Once positioned, the catheter may remain relatively fixed ata particular location within the artery by activating a stabilizingballoon (not shown) coupled to the catheter. The stabilizing member mayapply a mechanical force to an arterial wall to provide a frictionalforce that acts on and tends to keep the catheter in place within theblood vessel. The stabilizing member may be an inflatable positioning orsecuring balloon that is in communication with, and inflated by, aninflation lumen formed in the catheter body, or an expandable anchoringassembly such as a shape memory metal basket. When the deflectingmembers 242 are eventually actuated and moved to an open position, thedistal section of the deflecting member may spread apart or flare out ina substantially lateral direction away from the longitudinal axis of thecatheter. A mechanical force is thus applied to the area surrounding avascular occlusion or vessel wall by the deflecting members 242. Arelatively large spreading force may be observed at the distal most endof the deflecting member 242 upon actuation. In various embodiments ofthe invention, the deflecting member assembly 230 may be configured toexert approximately as much as up to 60 to 330 pounds of force persquare inch. The deflecting member assembly 230 may be furtherconfigured such that upon release of the pull member 232, the deflectingmember 242 may return to a closed position either actively or passively.

The deflecting members 242 described herein may be activated by variousactuation assemblies which spread apart or deflect the distal mostregion 244 of the members. An actuation assembly may be configured toproduce lateral movement in each hinged spreading member 242 of avascular tissue expansion assembly 230. Each spreading member 242 mayinclude a cam follower 234 formed on its interior portion. For example,the deflecting members or jaws 242 may be actuated by a cam 236 and camfollower 234 assembly positioned within the relatively interior portionof the deflecting members. A cam follower 234 may be formed as an angledor curved surface on the interior surface of a deflecting member 242. Acam 236 may be attached to the distal end of an actuation member 232that is positioned within a catheter shaft. The surface 238 of the cammay be formed with a variety of configurations including cylindrical,toroidal or spherical, and may have one or more shaped surface tocommunicate with a corresponding cam follower 234. The cam 236 may bealso configured as a central hub internally positioned within thedeflecting members 242. The cam 236 and cam follower 234 may beconfigured so that longitudinal movement of the actuation member 232, ineither a proximal or a distal direction, causes the surface or edge 238of the cam 236 to slidably move over the surface of the cam follower234. A spreading or actuating force is thus imparted on the tissueexpansion member 242 which opens or moves the distal end 244 of thedeflecting member 242 in lateral direction with respect to thelongitudinal axis of the catheter. The contours of the cam and camfollower surface may be configured to provide a selectable amount oflateral displacement or spreading force for the deflecting member 242.The ratio of lateral displacement of the deflecting members 242 per unitlongitudinal movement of the actuation member 232 and cam 236 may varygreatly including a range from approximately 1:1 to 2:1.

A hinged deflecting member assembly 250 may include a plurality ofhinges 254 as shown in FIG. 13. Each individual deflecting member 252may further include more than one hinge 254. The hinge section 254 ofeach expansion or deflection member 252 assist individual members inmoving between relatively open and closed positions. The hinge 254 mayalso provide arcuate or eccentric movement of the expansion member 252from a closed position to an open position with respect to thelongitudinal or central axis 251 of a catheter. The hinge 254 may bebiased so that the expansion member 252 may spread apart or deflect toan open position in response to an applied actuation force, which mayrange from but is not limited to approximately 0.25 to 8 lbs., and mayreturn to a closed position once the applied force is removed. Thespreading force may be applied to actuate the expansion members 252 byvarious mechanisms described herein such as pull or push tubes andwires, and cam assemblies (not shown). The deflection range of theexpansion members 252 may vary according to selected applications, andmay include a lateral bend or spreading angle of the tissue expansionmember of up to 45° or greater with respect to the longitudinal axis 251of the catheter.

The deflecting member assembly 250 shown in FIG. 13 may be integrallyformed from a single piece of suitable material or may include acombination of different components. Each deflecting or spreading member252 may be connected to a collar 256 with one or more hinges 254.Additional hinges 254 may provide additional lateral support for thedeflecting member 252 when moving between open and closed positions.Each hinge 254 may be separately formed of nitinol wire or otherflexible material, and may connect deflecting members to the collar 256.The collar 256 may be further mounted to a relatively distal portion ofa catheter shaft (not shown).

FIGS. 14A-D illustrate various configurations for tissue expansionmembers. As described above, vascular tissue expansion members may beformed with a wide variety of configurations and shapes. The expansionmembers 260 may be modified for particular applications, and may includevarious combinations of straight or linear proximal sections 262 withconcave, and relatively atraumatic, curved distal portions 264 as shownin FIG. 14A. Alternatively, the distal portion 274 of the expansionmember 270 may be formed with a convex curved distal end as illustratedin FIG. 14B. FIGS. 14C-D also provide other available modifications tothe distal end sections 284 and 294 of expansion members 280 and 290having a linearly and non-linearly tapered profiles, respectively, whichmay terminate with variably pointed tips 286 and 296 at the distal mostends of the expansion members. Other configurations may be of courseselected for the vascular tissue expansion members described herein forparticular applications.

The expandable displacement assemblies described herein may be actuatedby various mechanisms. As illustrated in FIGS. 15A-B, for example,distal mounted spreading members 302 may be actuated with an actuatingballoon 304 that spreads open the distal end portions 306 of spreadingmembers. The spreading or deflecting members 302 may be deflected in arelatively outward direction by the inflatable actuation balloon 304disposed within the deflecting member housing 300. The actuation balloon304 may be coupled to a relatively distal portion of a catheter 308, andmay be inflated through an inflation lumen in communication with aninflation device coupled to the proximal end of the catheter (notshown). The actuation balloon 304 may be made of known materialsincluding high strength polymers such as PET or irradiated polyethylene,and may be configured for multiple inflations to desired pressures. Theactuation balloon 304 may be configured to exert enough force on theinterior surface of deflecting members 302 to produce a spreading forceof up to approximately 60 to 330 pounds of force per square inch ormore. As with other pulling or pushing actuation assemblies describedherein, the spreading force may be modified according to appliedpressure and the relative size of deflecting members 302 and theinternally positioned actuation balloon 304 which may have an inflatedprofile of approximately 0.050″ to 0.200″.

An intravascular tissue expanding catheter, as shown in FIGS. 15A-B, mayinclude a catheter shaft 308 having at least one lumen or conduitextending along the longitudinal axis of the catheter shaft. A housing300 may be formed at the distal end of the catheter shaft 308 whereinthe housing may include at least one hinged deflecting member 302 havinga distal most tip 306 that moves in a substantially lateral directionaway from the central axis of the shaft to expand an area surrounding avascular occlusion. The deflecting member housing 300 may be furtherconstructed from multiple pieces or may be formed from a unitary pieceof deformable material. A slit 310 formed in the housing 300 maybasically provide a pair of deflecting members 302 with integrallyformed hinges. The selected material should support the opening andclosing movements of deflecting members 302, and should be relativelyrigid enough to apply the desired deflective force. An actuationassembly such as an expandable balloon 304 may be positioned along atleast some portion of the catheter shaft 308, or within the housing 300,to move or deflect the hinged deflecting member 302 away from thecentral axis of the shaft. An inflation conduit may be of course formedalong the longitudinal axis of the catheter shaft 308 leading to theexpandable balloon 304.

FIGS. 16A-D illustrate various tissue displacement assemblies formedwith a plurality of deflecting members. The displacement housingassembly 320 shown in FIG. 16A may be formed from single piece of formedmaterial, and may include multiple slits or openings 325 created bytechniques described herein to form several deflecting members 322 thatspread open when activated. The deflecting member assembly 320 may bemounted along a relatively distal portion of a catheter shaft 328. Anactuation member 334 positioned within the assembly housing 330, asshown in FIG. 16B, may include a cam 336 formed with a central hub orcurved surface for communication with cam followers 338 formed along theinterior portions of deflecting members 332. The actuation member 334may include a threaded section 337 that directs the cam 336 in arelatively distal or proximal direction when rotated in a particulardirection. The housing 330 may further include threaded portionsmatching the threaded section 337. The cam 336 may be moved in arelatively proximal direction by rotating the threaded tube 334 to openor urge the deflecting members 332 apart so that the cam 336 slidablycontacts adjacent cam followers 338 to spread apart the hinged spreadingmembers 332. The deflecting members 332 may be similarly closed byrotating the threaded tube 334 in a relatively opposite direction.

FIGS. 16C-D illustrates another deflecting member assembly 340 formedwith deflecting members 342 that have multiple hinges 343. The assembly340 housing may be also formed from a unitary piece of material, and mayinclude formed openings that accommodate arcuate movement of thedeflecting members 342. A cam 346 may be internally positioned withinthe housing 340, and may slidably contact cam followers 348 formed alongthe inner surface of deflecting members 342. The cam 346 may beconnected to a pull tube 344 at a relatively distal section, and may bedirected in a relatively proximal direction to spread apart the hingeddeflecting members 342. The deflecting member housing 340 may provide apinless or rivetless hinged section that supports deflection of at leastone deflecting member 342 when the pulling element 344 is pulled in arelatively proximal direction. The actuation tubes and assemblies shownin FIGS. 16A-D may be also formed with a guidewire lumen 321 to permitthe passage of a guidewire when the deflecting member assembly is eitheropened or closed. As with other cam configurations described herein, theinternally positioned cams may be formed of a variety of configurationsincluding spherical, frusto-conical or semi-planar.

The tissue expansion catheters described herein may also include singlehinged tissue displacing members 352 that are connected to an actuationor pulling element 355 as illustrated in FIGS. 17A-B. The tissueexpansion assembly 350 may comprise a hinged upper expansion member 352and a relatively fixed lower extension 354 of the assembly 350. Thetissue expansion member 352 may include a hinge pin assembly 360, andmay be pivotally attached to the lower extension 354 with a hinge pin362. The hinge pin assembly 360 may comprise a hinge pin socket formedalong a section of the upper expansion member 352 that may be alignedwith a corresponding hinge pin socket formed along the lower extension354. A hinge pin 362 may fit through both sockets to allow the upperexpansion member 352 to rotate about the hinge pin. The hinge pin 362may be externally threaded over a portion of its length, and may besecurely fastened into either socket, or held in place by press fit, bya nut or other mechanical attachment known in the art. The longitudinalposition of the hinge pin 362 may be positioned along any portion of theexpansion member assembly 350, and may be located about 0.200″ to 0.400″from the distal end of the assembly. The lower extension 354 of thetissue expansion assembly 350 may be formed with a proximal tubularsection and an elongated distal most section that includes a socket toreceive the hinge pin 362 for rotatably connecting the upper expansionmember 352. The lower extension 354 may also contain a lumen 358 alongat least a portion of its length for the placement and advancement of aguidewire.

As shown in FIG. 17B, the upper expansion member 352 may be spread apartor opened so that the distal end 353 of the expansion member is movedlaterally with respect to the longitudinal axis of the catheter. Thetissue expansion member 352 may be actuated by an attached pull wire355. The pull wire 355 may be rotatably attached to a relativelyproximal portion of the upper expansion member 352 by a pull wire pinand socket assembly 364. The pull wire 355 may be of course attached toother portions of the upper expansion member 352, and may be fastenedwith other known fastening method including welding or brazingtechniques. Additionally, the pull wire or member 355 may be formed ofstainless steel or other suitable materials, and may be formed with aflattened distal end section having a pull wire pin hole. The flatteneddistal end section may fit into a corresponding slot or groove formedwith corresponding pull wire pin holes in the upper expansion member352. A pull wire pin 366 may be press fit or otherwise secured in placeto hold the pull wire 355 and the upper expansion member 352 together.The upper expansion member 352 may pivot about the hinge pin 362 inresponse to a directed pulling force to the attached pull wire 355applied in a relatively proximal direction. The spreading angle of thetissue expansion member 352 may vary according to particularapplications and may range up to 45° or more. The hinge pin 362 and thepull wire pin 366 may be fabricated from hardened stainless steel orother suitable metals. It will be appreciated that other hingeconfigurations and known pivoting mechanisms may be equally applicableto this and other related embodiments described herein.

Additional intravascular catheters formed in accordance with theprinciples of the invention are illustrated in FIGS. 18A-D. Thecatheters may each include a catheter body formed with at least oneconduit and a single tissue expanding member connected to the distalsection of the catheter body. The expanding or deflecting member 368 maybe defined by a relatively proximal portion and a relatively distalportion. Upon actuation, the distal portion of the expanding member 368may be configured to rotate about or spread apart relative to itsproximal portion. The distal section of the catheter may further includea relatively fixed extension 362. The relatively proximal portion of thetissue expanding member 368 may be connected to the fixed extension 362with a hinge pin 366 to permit the relatively distal portion of thetissue spreading member to rotatably move away from the fixed extension.As shown in FIGS. 18A-B, a guidewire lumen 363 may be formed in a lowerextension member 362 that is concentric or centered with respect to thelongitudinal axis of the catheter 360. As shown in FIG. 18B, theguidewire lumen 363 may thus fit in between the pull wire pin 364 andthe hinge pin 366 which are both positioned substantially across theexpansion member assembly. This configuration may provide a relativelylarge guidewire lumen 363 to accommodate a wide variety of guidewires ordevices with diameters of up to 0.035″ or greater. The guidewire lumen363 may further include an inner liner tube or guidewire tube extension365 that may extend along the full length or discrete sections of thecatheter 360 or the lower tissue expansion member 362. The inner linertube 365 may be formed from a variety of materials including nitinol,high strength polymers such as polyimide, lubricious polymers such asTeflon. The hinged deflecting member 368 may be also formed with acurved or contoured surface to fit around the inner liner tube 365 whenit is placed in closed position as shown in FIG. 18B. Alternatively, asshown in FIGS. 18C-D, the guidewire lumen 363 may be positionedoff-center with respect to the axis of the catheter 370. In thisconfiguration, the hinge pin 366 may be positioned in between the pullwire pin 364 placed across the upper expansion member 368 and theguidewire lumen 363 when viewed in cross-section as shown in FIG. 18D.Similarly, an inner lining tube 365 may be positioned within theguidewire lumen 363, and may extend along the entire length or discreteportions of the catheter shaft and/or expansion member assembly.

A guidewire 380 may be passed through various lumens formed alongdifferent portions of the intravascular catheters described herein asshown in FIGS. 19A-E. Although a guidewire may be commonly used toposition the catheters in an area near a vascular occlusion, a guidewiremay be of course positioned through a portion or across the obstructionafter the occlusion is displaced by device. The intravascular cathetermay further include a guiding tube externally attached to a section ofthe catheter or along the entire length of the catheter. As shown inFIG. 19A, a guiding tube 382 may be positioned along a relatively distalportion of the catheter to receive a guidewire 380. The guiding tube 382may terminate prior to the proximal section of a lower expansion member388 so that the guidewire 380 exits the guiding tube proximal to thelower expansion member. Alternatively, as illustrated in FIG. 19B, theguiding tube 392 may extend into, or may be coupled to, anotherguidewire lumen 394 formed in a relatively lower extension member 398such that a guidewire 380 exits from the distal end of lower extensionmember. The guidewire guiding tube 392 can be made from a wide varietyof materials including formable polymers such as polyimide andpolyethylene, or from a metal hypotube made of stainless steel ornitinol. As shown in FIG. 19C, a guidewire lumen 384 may also extendalong at least a distal portion of the catheter shaft 386 and anexpansion member 385. FIGS. 19D-E illustrates a guidewire lumen 393formed in the catheter shaft 396 and partially within an expansionmember 395. The guidewire lumen 393 in the expansion member 395 may beenclosed or partially exposed to the exterior surface of the catheter.At least a distal portion of the catheter may thus ride along aguidewire 380 in a monorail fashion. These and similar configurationsfor positioning a guidewire lumen are included herein including otherdifferent regions along the catheter shaft and expansion memberassembly.

FIGS. 20A-C illustrate other vascular tissue expansion assemblies formedin accordance with the invention. The tissue expansion assembly 400shown in FIGS. 20A-B may include a single hinged spreading member 402formed by methods similar to those previously described. The hingedspreading member 402 may include a curved interior portion formed with acam follower 406. The distal section of the catheter shaft 405 or theexpansion assembly 400 may also include a relatively fixed or stationaryextension 404 formed with a cam follower having a co-linear bearingsurface 408 with respect to the longitudinal axis of the catheter. A cam410 formed with complementary surfaces 413 may be internally positionedwith the tissue expansion assembly 400. The cam 410 may be configuredfor slidable movement along the co-linear bearing surface 408 and theinternal cam follower 406 formed along an interior portion of the singlehinged spreading or deflecting member 402. An actuation member or pullwire 412 may be connected to the cam 410 to move the distal most tip 414of the spreading member 402 in a substantially lateral direction awayfrom the longitudinal axis of the catheter. An actuation conduit 416 maybe formed along a portion of the expansion assembly 400 and the cathetershaft 405. The pulling element or pull wire 412 may be positionedrelatively proximal to the cam 410 within the actuation conduit 416. Aguidewire lumen 418 may be similarly formed through at least a portionof the expansion assembly 400 or catheter shaft 405.

The cam assembly shown in FIGS. 20A-B may include an irregularly shapedcam 410 and cam follower 406 formed on a single hinged deflecting member402. A wide variety of configurations may be selected for the cam 410,which may be symmetrical and asymmetrical as shown herein, and mayinclude one or more contoured or relatively linear surfaces 413. The camfollower 406 may be formed by machining the interior surface of thedeflecting member using various known techniques including precisionmachining methods such as CNC or EDM techniques. The cam follower 406and deflecting member 402 may be alternatively manufactured and formedfrom a cast heat treated metal part or molded plastic part. The cam 410may be formed of stainless steel or engineered plastics such aspolycarbonate, Dehrin or Teflon with high strength and relatively lowsurface friction. The cam 410 may be also attached to an actuationmember 412 such as a pull tube using adhesive bonding, crimping,soldering, welding or other joining well known methods. The surfaces ofthe cam and/or cam follower may be also coated with a lubricous polymercoating such as Teflon to reduce friction therebetween.

FIG. 20C illustrates another tissue displacement assembly 420 that maybe positioned along a relatively distal portion of an intravascularcatheter. A push tube 421 may be positioned within the actuation conduit426 to deflect the distal end 424 of the displacing member 422 away fromthe catheter axis in response to a distally directed force. The pushtube 421 may be positioned relatively proximal to a cam follower 428within the actuation conduit 426 which may be formed of a variety oflinear or curved surfaces. As described earlier, these various actuationmechanisms described herein may be used in accordance with other aspectsand variations of the invention.

A rotationally actuated deflecting assembly 430 and 440 is furtherprovided in accordance with the invention as shown in FIGS. 21A-B. Thelateral movement of the vascular tissue expansion member may begenerated by a rotational movement of an actuation member about thelongitudinal axis of the catheter. As shown in FIG. 21A, the camfollower 434 may be formed as a spiral groove on the interior surface ofat least one expansion member 432. The cam 436 may include a spiralthread or ridge attached to the actuation member 435. The vasculartissue assembly 430 may further include a relatively fixed extension 438formed with another cam follower having complementary grooves 437. Whenthe actuation member 435 is rotated about the catheter axis, the cam 436may contact the cam followers 434 and 437 and spread apart the expansionmember 432. Alternatively, as illustrated in FIG. 21B, the cam follower444 may be formed as a groove or notch along the interior portion of thetissue expansion member 442. The relatively fixed extension 448 of theexpansion assembly 440 may be also formed with a cam follower 447 with aenlarged groove. A cam 446 may include an offset curved surface orprotuberance that slidably fits within the groove of the extension 448when the expansion member 442 is in a closed position. However, when theactuation member 445 is rotated about the catheter axis, the curved cam446 surface may slidably rotate and communicate with the cam followers444 and 447 to spread open the expansion member 442. Although theillustrations provided show single expansion members, it is understoodthat similar rotational actuation mechanisms may be applied toassemblies with multiple expansion members.

FIGS. 22-24 provide various catheter shaft configurations that may beselected for the intravascular devices described herein. Anintravascular catheter for expanding tissue may basically include a bodythat is formed with an outer reinforced shaft coaxially formed about aninner coiled body for column load reinforcement of the catheter body.The inner coiled body may be also formed with an actuation conduit. Thecatheter may further include a distally mounted tissue expanding memberand an actuation element positioned within a conduit formed within thecatheter shaft. The catheter shaft may exhibit a unique combination ofdimensional and mechanical properties that permit their passage throughtortuous vasculature including coronary, cerebral or peripheral bloodvessels. The flexibility and column load bearing characteristics ofthese catheter shafts support the transmission or delivery of sufficientspreading or disrupting forces to push through or spread apartobstructed vascular regions in order to form channels across anocclusion. The dimensional properties of the intravascular cathetersinclude a relatively small diameter throughout the length of thedevices, and a relatively low-profile to minimize obstruction ofcirculatory function. The structural and mechanical properties of thecatheter shafts further include a combination of compressive andtorsional strength with sufficient rigidity, together with lateralflexibility, particularly at the more distal sections of the catheter.The outside diameter for the relatively distal end portions of thecatheter may widely range for particular applications including fromapproximately 0.014″ to 0.200″. For coronary applications, the outerdiameter may range from approximately 0.014″ to 0.092″, including apreferable range of 0.039″ to 0.78″. For peripheral applications, arange of 0.070″ to 0.200″ may be selected. The materials andconstruction of the catheter may be configured to allow the medicalpractitioner to transmit the required or appropriate longitudinal forcefrom a remote or proximal end of the relatively small diameter catheteracross a substantial distance to a relatively distal end portion of thecatheter. An actuation member such as a pull wire or tube may bedirected in a relatively proximal direction at a remote or proximallocation to spread apart or deflect distal mounted tissue displacingmembers. This may be accomplished, in part at least, through the use ofa relatively stiff shaft to support the column load which may be formedfrom high density polyethylene or polyimide, and wire braid orstiffening wire. The catheter may also have a sufficient length toposition the hinged deflecting members in the coronary or peripheralvasculature from a femoral, brachial or carotid approach. Typicallengths for these applications include, but are not limited to, a rangefrom about 60 to 200 cm, including a preferable range for coronaryapplications from 120 to 160 cm. A preferable working length of 80 to120 cm may be selected for peripheral applications. The vascular tissueexpanding assembly may be positioned in various blood vessels such ascoronary, cerebral and peripheral arteries. Expanding members may bemaneuvered to and positioned at or near the anastomoses or juncture of abypass graft and a coronary artery, including at or near a substantiallyoccluded artery. The intravascular catheters provided herein mayre-establish a channel or lumen of sufficient size in the native bloodvessel to provide a pathway for placement of a guidewire across a totalocclusion for subsequent use with primary therapies such as PTA, PTCA,and stenting.

The catheter shaft may basically include an outer catheter shaft formedwith a longitudinal shaft lumen. An inner coiled body may be positionedwithin the longitudinal shaft lumen for column load reinforcement of theouter shaft. The inner coiled body may be also formed with alongitudinal coiled lumen to receive a pulling element or tube toactuate a distally mounted tissue displacement assembly. The movablepulling element may be slidably positioned within the longitudinalcoiled lumen for relative movement of the pulling element with respectto the inner coiled body. This inner coiled and outer shaftconfiguration may provide flexibility and improved transmission ofcolumnar force over the length of the catheter. The relatively distalportions of the catheter may be thus advanced into narrowed and tortuousvasculature including coronary blood vessels where distal mountedvascular tissue expansion assemblies may be actuated to provide aspreading force to displace a vascular occlusion.

The outer catheter shaft may be formed of various durable material orsuitable polymers and have a reinforcing member positioned around theexterior walls of a catheter. The outer catheter shaft may be braidreinforced, and may have an outer diameter ranging from approximately0.025″ to 0.080″. Of course, these dimensions may vary according toparticular applications. The reinforcing member may be a braided shaftmember to improve the overall torsional strength of the catheter shaft.The reinforcing member may be a metal braid, a hypotube or a stiffenedpolymer tube such as HDPE. The reinforcement member may be also formedof a flat stainless steel wire braid coated with polyurethane which is,in turn, disposed over an inner core of polyimide (available from HVTechnology, GA). Alternatively, the reinforcement member may be formedof a stainless steel braid encapsulated in pebax tubing available fromTFX Medical Corp., NH.

The inner diameter of the lumen formed in the outer shaft may be varied,and may range between approximately 0.028″ to 0.030″ or more toaccommodate a coiled inner shaft. A coiled inner shaft may have anappropriate outer diameter to fit within the outer shaft, and may rangebetween approximately 0.027″ to 0.029″ or more. These relativedimensions may be of course varied for particular vascular applications.In a preferable embodiment, the force transmission characteristics ofthe coiled shaft may be achieved with an outer diameter that is no morethan 0.003″ smaller than the inner diameter of the outer shaft. Thecoiled shaft may be further constructed of stainless steel or steel witha silicon content as high as 2%, and may be formed with a tight pitchwind that may provide intimate contact between adjacent coils. Thecoiled shaft may transmit or sustain a columnar force of up to 50 lbswithout significant coil filer overlap or increase in the outer diameterof the coiled shaft. The inner coiled body may be closely wound, and mayhave a proximal portion that includes a hypotube.

The pull member may be a pull tube made of stainless steel or a hypotubeformed of nitinol available from Memry Inc., CA. The pull member may beselected or configured to limit the amount of longitudinal force appliedby the physician to the vascular tissue expanding assembly. Apreselected amount of force may be established for the pull member sothat amounts of force applied in excess of the selected limit willmerely deform the pull member and will not be transmitted to expandingmembers. A preferable range for a predetermined amount of longitudinallyapplied force may include between 5 to 10 lbs of force. This may beachieved by configuring a pull tube to elastically deform at loads at ornear 5 to 10 lbs with complete elastic recovery for strains up to 8%.This property can be achieved by the use of super elastic metals such asnitinol provided by Shape Memory Alloys, Inc., CA.

The positioning of the actuation or pull member, the guidewire, and thecoil, may be varied with respect to the central axis of the catheter.These components may be located concentrically or off-center within thecatheter body. In one embodiment, as shown in FIGS. 22A-B, the cathetershaft 450 may be formed with a concentric or coaxial design with respectto both the pull member 452 and the guidewire 451 relative to thecatheter central axis. The outer catheter shaft 454 may be formed with asingle lumen to accommodate an inner coiled shaft 453. The inner coiledshaft 453 may be similarly formed with an coiled shaft lumen forslidable movement of a pull member or pull tube 452. The pull tube 452may be also formed with a lumen 455 for positioning of a guidewire 451therethrough. The inner diameter of the outer shaft 454 may accommodatethe inner coiled shaft 453. Similarly, the inner diameter of the innercoiled shaft 453 may provide for slidable movement of a pull tube 452.The pull tube 452 may also have a sufficient inner diameter to allowslidable movement of a guidewire 451 positioned therein. The innercoiled shaft 453 may allow the overall catheter shaft 450 to sustain thetransmission of a columnar or longitudinal force over the length of thecatheter without a substantial compression of the catheter shaft andresultant loss of force transmission. The outer shaft body 454 mayassist in retaining the coiled shaft 453 in proper alignment to avoidcoil filer overlap. The filers within the coiled shaft 453 may not benecessarily rounded, and may be relatively flat to provide an increasedcontact surface with neighboring coils. The inner coiled shaft 453 maythus provide increased flexibility over a similarly dimensioned tubewhile providing sufficient column load bearing properties to thecatheter shaft 450 without significant increase in the diameter of thecoiled shaft due to the overlapping of adjacent coils when the force isapplied. This overall construction may allow the catheter shaft totransmit torque and sustain a column load while still providingsufficient flexibility to a physician to navigate a catheter devicethrough tortuous vasculature.

As shown in FIGS. 23A-B, a catheter shaft 460 may include one or morelumens longitudinally extending over the entire length or along apredefined portion of the catheter. The lumens may be adapted for theplacement and advancement of various devices including guidewires, pullwires, spring wires, catheters, and optics. The catheter may furtherinclude ports for the delivery of gas and fluids such as air, saline,and contrast solutions. In various embodiments of the invention,catheter shafts may include lumens that are concentrically oreccentrically (off-centered) formed within the catheter. A wide range ofavailable geometries for the lumens are of course available and mayinclude but is not limited to cross-sectional shapes that are circular,semi-circular or oval shaped.

An inner shaft 465 may be extruded from polyethylene or similar materialwith a dual lumen configuration to provide a guidewire lumen and aseparate pull tube or wire lumen. A coil 463 may include a pull tube orwire lumen and contain an actuation member 462 disposed therein. Aguidewire 461 and pull tube or wire 462 may thus have an eccentric oroff-center relationship. The guidewire lumen and pull tube lumen may beof course formed in other positions relative to one another within theinner shaft. The inner catheter body 465 may be formed from a variety offlexible medical polymers including polyimide, pebax, polyethylene,polyurethane, silicone. Additionally, pliable metal hypotubing such asstainless steel or nitinol may be selected which may be both polymercoated. The inner shaft 465 may be formed from copolymers and othercombinations of the aforementioned polymers known to those skilled inthe art, and may be formed by known extrusion methods with single ormultiple lumens. The catheter body may also comprise multi-laminatedtubing or joined longitudinal sections of tubing made from one or moreof the aforementioned polymers and components.

The catheter shaft 460 illustrated in FIGS. 23A-B may include areinforced outer catheter shaft 464 formed with an outer shaft lumen,and an inner shaft 465 positioned within the outer shaft lumen that isformed with an actuation lumen and at least one inner shaft lumen. Acolumn load reinforcement coil 463 formed with a coil lumen may bepositioned within the actuation lumen, and an actuation wire 462 may beslidably positioned within the coil lumen to provide relative movementof the wire. The coil 463 may further include an additional sleeve (notshown) surrounding the coil or coil lumen. An inner shaft lumen may beconfigured for placement of a guidewire 461, and may be formed in aside-by-side or non-concentric configuration relative to the actuationlumen.

FIGS. 24A-B illustrate an outer catheter shaft 470 that may include twoseparate internal conduits or tubes 475 and 478 for a guidewire, and fora pull tube and coil assembly. The reinforced catheter body 470 mayinclude a braid reinforced catheter shaft 474 formed with a longitudinalcatheter shaft lumen 477. An actuation conduit 475 may be formed with alongitudinal actuation conduit lumen, and may be positioned along with aguidewire conduit 478 within the longitudinal lumen 477 of the cathetershaft. Moreover, a coiled support tube 473 formed with a coiled tubelumen may be positioned within the actuation conduit lumen for columnload reinforcement of the actuation conduit 475. A pulling element 472may also be positioned within the coiled tube lumen for relativeslidable movement within the support tube 473.

As shown in FIGS. 25A-C, the actuation or pull members 481 describedherein may be coupled at its proximal end to a pulling mechanism 480 toprovide longitudinal movement of the member. The pulling mechanism 480may comprise a handle 482 that is pivotally attached to a lever arm 484with a lever pin 486. The lever arm 484 may be fixedly attached to aproximal adaptor 488 that is further connected to the proximal end of acatheter 490. The lever 484 may fit into the handle 482 at a slot 485 asillustrated in FIG. 25B. The dimensions of the slot 485 may be selectedwith respect to the relative dimensions of the mating end of the lever484 to limit the longitudinal movement of the lever to a predeterminedor fixed amount. In a related embodiment shown in FIG. 25C, a ratchetmechanism 495 may be employed at the mating surfaces of the handle 482and the lever 484 to control the longitudinal movement of the lever 484to fixed increments.

The proximal adaptor shown in FIG. 25A may include one or more ports 492for passage of a variety of materials described herein including fluidand gas introduction. The ports 492 may further have O-ring valves orluer fittings at their relatively proximal ends to provide improvedseals. One or more ports 492 may have lumens which are fluidically orspatially coupled to lumens within the catheter 490. The proximaladaptor 488 may be made of an injection molded plastic or other commonlyused materials. The proximal end of the pull member 481 may be attachedto the lever 484 so that when the lever is pulled proximally by aphysician, the lever pulls the pull member proximally. The handle 482and lever 484 may be made from high strength injection molded plasticsor other suitable materials. For embodiments utilizing a pull tube 481,the proximal end of the pull tube may be attached to the proximal end ofthe handle 482. The pull tube 481 may further include a guidewireintroducer 494 attached at its proximal end to facilitate introductionof a guidewire 496 into the pull tube. The introducer 494 may havevarious configurations including a cone or funnel shape, and may be madefrom lubricious plastics.

Another aspect of the invention provides methods of displacing ordisrupting a vascular occlusion as shown in FIGS. 26A-B. Anintravascular catheter 500 may be selected having one or more spreadingmembers 502 positioned at the distal region of the catheter that isresponsive to directed force along the longitudinal axis of thecatheter. The directed force may be provided by an actuator assembly 510positioned along the catheter to transmit or relay a directed forceapplied from a relatively proximal portion of the catheter to therelatively distal spreading member 502. The vascular catheter 500illustrated in FIG. 26A may be positioned adjacent to a substantially ortotally vascular occlusion 501 in an initially closed position within aselected blood vessel 503. As shown in FIG. 26B, a directed force may beapplied through the actuator assembly 510 to deploy or spread apart thespreading members 502 into an open position in order to displace thevascular occlusion 510. The spreading member 502 may displace or disrupttissue surrounding or in the vascular occlusion 501 to create a pathsubstantially through or around the occlusion. The blood vessel wall 505may be also stretched to create a path substantially between theocclusion 501 and the blood vessel wall. When a vascular occlusion isadhered to the wall of the selected blood vessel, the spreading member502 may possibly spread apart the separate the layers of the bloodvessel wall 505. Some or all of these conditions may occur whendisplacing a vascular occlusion in accordance with apparatus and methodsprovided herein which often results in providing a path formed with theleast or minimal amount of mechanical resistance. In addition, thevascular catheter 500 may be distally advanced along the path formedthrough or around at least a portion of the occlusion 501. A guidewire515 may be alternatively selected and passed through a lumen or conduitto the site of the occlusion 501, and may be advanced around or throughat least a portion of the occlusion. The vascular catheter 500 may beremoved from the blood vessel 503 before or thereafter, or may be evenmaintained in position to carry out desired procedures such as placementof the guidewire 515 across the occlusion 501 through the dissectedchannels provided by the catheter. This separation or displacement of anocclusion within a blood vessel may be attributed at least in part tothe difference in elasticity of a vascular occlusion and a blood vesselwall. For example, deposited plaque within arterial walls may beconsidered relatively brittle compared to relatively stretchablearterial wall. The obstruction may be thus fractured or broken up withreduced risk of compromising the blood vessel wall.

Another method of crossing a substantially occluded blood vessel isfurther provided in accordance with the invention as illustrated inFIGS. 27A-B. An intravascular catheter may be selected having a distallymounted tissue displacing assembly 600. The assembly 600 may include atleast one tissue displacing member 602 having a relatively proximalportion 604 and a relatively distal portion 606 so that the distalportion is configured to expand relative to the proximal portion of theexpanding member. The tissue displacing member 602 may be alsoconfigured to rotate about one end thereof. An actuation assembly 608may be positioned within the intravascular catheter to transmit aspreading force to expand the distal portion 606 of the expanding member602. The tissue expanding member 602 may be placed within a target bloodvessel 601 in proximity to an occlusion 603. A guiding catheter 607 maybe selected to position the intravascular catheter as shown with orwithout a guidewire 609. The tissue displacing assembly 600 may beactivated so that displacing member 602 may extend and stretch the areasurrounding blood vessel wall 605 thereby disrupting the occlusion 603to permit the passage therethrough. The distal portion 606 of the tissueexpanding member 602 may have an original diameter before actuation, andthe distal portion 606 may expand to an enlarged diameter that is equalto at least approximately one-hundred and ten percent of its originaldiameter. The tissue displacing member 602 may be also controllablyactivated to provide intermittent expansion, and may be eventuallydeactivated thereafter and removed from the blood vessel 601.

Another method of crossing a vascular occlusion involves the selectionand advancement of a guidewire within a blood vessel to the site of avascular occlusion. As shown in FIGS. 28A-B, a guiding catheter assembly701 including an intra-coronary catheter 702 may be positioned over aguidewire 703 so that the distal end of the intra-coronary guidingcatheter is in proximity or in contact with a vascular occlusion 705such as a chronic total occlusion in the heart region. After removingthe guidewire 703 from the blood vessel, as shown in FIG. 28C, anintravascular catheter 710 having at least one lumen may be insertedinto the guiding catheter 701 within the blood vessel as shown in FIG.28D. The intravascular catheter 710 may further include a spreading ortissue displacing member positioned at the distal region of the catheterthat is responsive to directed force along the longitudinal axis of thecatheter. An actuator assembly as described herein (not shown) may bepositioned at least in part within the catheter 710 to transmit adirected force applied from the proximal portion of the catheter to thespreading member. The intravascular catheter may be advanced through theguiding catheter assembly 701 to position the spreading member of theintravascular catheter substantially adjacent to or at least partiallywithin the vascular occlusion 705. A directed force may be providedthrough the actuator assembly to spread apart the tissue displacingmember in order to displace the tissue surrounding the vascularocclusion 705. The intra-coronary guiding catheter 702 and/or theintravascular catheter 710 may be advanced past the occlusion 705 beforeremoval from the blood vessel as shown in FIGS. 28E-F. As shown in FIG.28G, the intravascular catheter 710 may be retracted leaving theintra-coronary guiding catheter 702 in position across the occlusion705. A guidewire 703 may be placed across, past or relatively distal tothe displaced vascular occlusion 705 after or before removing theintravascular catheter 710 and/or a portion of the guiding catheterassembly 701 as shown in FIGS. 29H-I. It should be understood that anycombination of one or more of the preceding steps may be performed orrepeated in a variety of sequences to cross an occlusion located in anyblood vessel.

While all aspects of the present invention have been described withreference to the aforementioned applications, this description ofvarious embodiments and methods shall not be construed in a limitingsense. The aforementioned is presented for purposes of illustration anddescription. It shall be understood that all aspects of the inventionare not limited to the specific depictions, configurations or relativeproportions set forth herein which depend upon a variety of conditionsand variables. The specification is not intended to be exhaustive or tolimit the invention to the precise forms disclosed herein. Variousmodifications and insubstantial changes in form and detail of theparticular embodiments of the disclosed invention, as well as othervariations of the invention, will be apparent to a person skilled in theart upon reference to the present disclosure. It is thereforecontemplated that the appended claims shall cover any such modificationsor variations of the described embodiments as falling within the truespirit and scope of the invention.

What is claimed is:
 1. A catheter for treating a vascular occlusion,comprising: an elongated shaft including a proximal section and a distalsection, wherein the shaft is formed with at least one lumen extendingfrom the proximal section to the distal section; at least one spreadingmember formed at the distal section of the shaft, wherein the at leastone spreading member comprises a free distal end that moves through anarc away from the longitudinal axis of the shaft with respect to a fixedpivotal position of a proximal end of the spreading member to disrupt avascular occlusion, wherein the at least one spreading member includes arelatively interior portion formed with a cam follower; and an actuatingassembly positioned along the elongated shaft to move the free distalend of the at least one spreading member in response to an actuationforce, wherein the actuating assembly includes an actuation elementincluding a distal end and a cam formed at the distal end forcommunication with the cam follower.
 2. The catheter of claim 1, whereinthe cam is configured as a central hub that slidably contacts the camfollower formed on the interior portion of the at least one spreadingmember when the cam is moved in a relatively proximal direction to movethe distal most end of the at least one spreading member in asubstantially lateral direction.
 3. The catheter of claim 1, wherein thecam is formed with a cam edge that slidably contacts the cam followerformed on the interior portion of the at least one spreading member whenthe cam is moved in a relatively distal direction to move the distalmost end of the at least one spreading member in a substantially lateraldirection.
 4. The catheter of claim 1, wherein the distal section of theelongated shaft includes a nosecone.
 5. The catheter of claim 1, whereinthe distal section of the elongated shaft includes a hub defined by anexternal surface, wherein a collar section is fitted around the externalsurface of the hub.
 6. The catheter of claim 1, wherein the at least onespreading member includes at least two hinged spreading members joinedto the collar section as a unitary body.
 7. The catheter of claim 1,wherein the at least one spreading member is defined by a substantiallycurved end.
 8. The catheter of claim 1, wherein the at least onespreading member is defined by a substantially tapered end.
 9. Thecatheter of claim 1, wherein the at least one spreading member isdefined by a substantially pointed end.
 10. An intravascular tissueexpanding catheter, comprising: a catheter shaft including a distal endand a longitudinal axis having at least one conduit extending along thelongitudinal axis, a housing formed at the distal end of the cathetershaft wherein the housing includes at least one deflecting memberdefined by a proximal end pivotally coupled to the catheter shaft and afree distal tip that moves through an arc away from the longitudinalaxis of the shaft to expand vascular tissue, wherein the at least onedeflecting member includes an integrally formed hinge; and an actuationassembly positioned along the catheter shaft to move the distal tip ofat least one deflecting member away from the longitudinal axis of thecatheter shaft.
 11. The intravascular catheter of claim 10, wherein theat least one deflecting member includes a plurality of hinges.
 12. Theintravascular catheter of claim 10, wherein the actuation assemblyincludes a pulling element connected to the at least one deflectingmember.
 13. The intravascular catheter of claim 12, wherein the at leastone deflecting member is connected to the housing with a at least onehinge pin to form a at least one hinge that supports rotation of the atleast one deflecting member when the pulling element is pulled in arelatively proximal direction.
 14. An intravascular tissue expandingcatheter, comprising: a catheter shaft including a distal end and alongitudinal axis having at least one conduit extending along thelongitudinal axis; a housing formed at the distal end of the cathetershaft wherein the housing includes at least one deflecting memberdefined by a proximal end pivotally coupled to the catheter shaft and afree distal tip that moves through an arc away from the longitudinalaxis of the shaft to expand vascular tissue, wherein the at least onedeflecting member is formed with an internal cam follower; and anactuation assembly positioned along the catheter shaft to move thedistal tip of at least one deflecting member away from the longitudinalaxis of the catheter shaft.
 15. The intravascular catheter of claim 14,wherein the actuation assembly includes a cam positioned within thehousing for slidable movement along the cam follower of the at least onedeflecting member to move the distal tip of the at least one deflectingmember.
 16. The intravascular catheter of claim 15, wherein theactuation assembly includes an actuation conduit formed along thecatheter shaft and a push tube positioned relatively proximal to the camfollower within the actuation conduit.
 17. The intravascular catheter ofclaim 15, wherein the actuation assembly includes an actuation conduitformed along the catheter shaft and a rotational tube positionedrelatively proximal to the cam within the actuation conduit.
 18. Theintravascular catheter of claim 15, wherein the actuation assemblyincludes an actuation conduit formed along the catheter shaft and apulling element positioned relatively proximal to the cam followerwithin the actuation conduit.
 19. An intravascular tissue expandingcatheter comprising: a catheter shaft including a distal end and alongitudinal axis having at least one conduit extending alone thelongitudinal axis, wherein the catheter shaft is defined by an externalsurface and a guidewire conduit is formed within the external surface ofthe catheter shaft, wherein the guidewire conduit is formed offset fromthe longitudinal axis of the catheter shaft; a housing formed at thedistal end of the catheter shaft, wherein the housing includes at leastone deflecting member defined by a proximal end pivotally coupled to thecatheter shaft and a free distal tip that moves through an arc away fromthe longitudinal axis of the shaft to expand vascular tissue; and anactuation assembly Positioned along the catheter shaft to move thedistal tip of at least one deflecting member away from the longitudinalaxis of the catheter shaft.
 20. An intravascular tissue expandingcatheter, comprising: a catheter shaft include a distal end and alongitudinal axis having at least one conduit extending along thelongitudinal axis, wherein the catheter shaft is defined by an externalsurface and a guidewire conduit is formed along the external surface ofthe shaft; a housing formed at the distal end of the catheter shaftswherein the housing includes at least one deflecting member defined by aproximal end pivotally coupled to the catheter shaft and a free distaltip that moves through an arc away from the longitudinal axis of theshaft to expand vascular tissue; and an actuation assembly positionedalong the catheter shaft to move the distal tip of at least onedeflecting member away from the longitudinal axis of the catheter shaft.21. An intravascular catheter for use in vasculature, comprising: acatheter body that includes a distal section and at least one conduit,wherein the distal section includes a fixed extension; at least onetissue expanding member connected to the distal section of the catheterbody, wherein the tissue expanding member includes a proximal portionand a distal portion wherein the proximal portion is connected to thefixed extension with a hinge pin so that the distal portion is free andconfigured to move through an arc away from the longitudinal axis of thecatheter body relative to the fixed pivotal position of the proximalportion of the tissue expanding member; an actuation assembly positionedwithin the catheter body in communication with the tissue expandingmember to move the distal portion of the tissue expanding member,wherein the actuation assembly includes an actuation member coupled tothe proximal portion of the tissue expanding member with an actuationmember attachment; and a guidewire lumen positioned between the hingepin and the actuation member attachment within the distal section of thecatheter body.
 22. The intravascular catheter of claim 21, furthercomprising a guidewire tube extension defined by an outer surfacepositioned along at least a portion of the fixed extension for enclosinga guidewire.
 23. The intravascular catheter of claim 22, wherein the atleast one tissue expanding member is formed with a surface that iscomplementary to the outer surface of the guidewire tube extension.